Anaesthetics: Pain and pain relief Flashcards
(38 cards)
What is pain?
○ Pain is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”
○ Pain is what the patient says it is ….
Why treat pain?
○ 1 in 4 people live with persistent pain
○ Basic Human Right
○ 66% of people attending A & E seeking help with pain had made around 3 visits to HCP in proceeding weeks
○ Person living with pain has poor quality of life as bad as other neurological diseases
○ Low Back Pain is the number 1 disease for years lost to disability worldwide
What are the benefits to treating pain?
○ For the patient - Physical □ Improved sleep, better appetite □ Fewer medical complications (e.g. heart attack, pneumonia) - Psychological □ Reduced suffering □ Less depression, anxiety ○ For the family - Improved functioning as a family member (e.g. as a father or mother) - Able to keep working ○ For society - Lower health costs (e.g. shorter hospital stay) - Able to contribute to the community
What are the different ways to classify pain?
- Duration • Acute • Chronic • Acute on chronic - Cause • Cancer • Non-cancer - Mechanism • Nociceptive • Neuropathic
What is the difference between acute and chronic pain?
- Acute □ Pain of recent onset and probable limited duration - Chronic □ Pain lasting for more than 3 months □ Pain lasting after normal healing □ Often no identifiable cause
What is the difference between cancer and non-cancer pain?
- Cancer pain □ Progressive □ May be a mixture of acute and chronic - Non-cancer pain □ Many different causes □ Acute or chronic
What is nociceptive pain?
- Obvious tissue injury or illness
- Also called physiological or inflammatory pain
- Protective function
- Description
□ Sharp ± dull
□ Well localised
What is neuropathic pain?
- Nervous system damage or abnormality
- Tissue injury may not be obvious
- Does not have a protective function
- Description
□ Burning, shooting ± numbness, pins and needles
□ Not well localised
What are the 4 steps of pain physiology?
□ Periphery
® Tissue injury
® Release of chemicals e.g. Prostaglandins, Substance P
® Stimulation of pain receptors (nociceptors)
® Signal travels in Aδ or C nerve to spinal cord
□ Spinal cord
® Dorsal horn is the first relay station
® Aδ or C nerve synapses (connects) with second nerve
® Second nerve travels up opposite side of spinal cord
□ Brain
® Thalamus is the second relay station
® Connections to many parts of the brain ◊ Cortex ◊ Limbic system ◊ Brainstem
® Pain perception occurs in the cortex
□ Modulation
® Descending pathway from brain to dorsal horn
® Usually decreases pain signal
What is the reason reason for neuropathic pain?
- Abnormal processing of pain signal
- Nervous system damage or dysfunction
- Needs to be treated differently
- Examples
□ Nerve trauma, diabetic pain (damage)
□ Fibromyalgia, chronic tension headache (dysfunction) - Pathological mechanisms
□ Increased receptor numbers
□ Abnormal sensitisation of nerves ® Peripheral ® Central
□ Chemical changes in the dorsal horn
□ Loss of normal inhibitory modulation
Give examples of simple analgesics
- Paracetamol (acetaminophen)
- Non-Steroidal Anti-inflammatory drugs
□ Diclofenac, ibuprofen
Give exaamples of opiods
- Mild
□ Codeine, Dihydrocodeine - Strong
□ Morphine, Oxycodone, Fentanyl
Give examples of analgesics other than simple analgesics and opiods
- Tramadol ( Mixed opiate and 5HT/NA reuptake inhibitor)
- Antidepressants (e.g. amitriptyline, duloxetine)
- Anticonvulsants (e.g. gabapentin)
- Ketamine (NMDA Receptor antagonist)
- Local anaesthetics
- Topical agents (e.g. Capsaicin)
What treatments for pain affect the peripheries
- Non-drug treatments
□ Rest, ice, compression, elevation - Non-steroidal Anti-inflammatory drugs
- Local anaesthetics
What treatments for pain affect the spinal cord?
- Non-drug treatments □ Acupuncture, massage, TENS - Local anaesthetics - Opioids - Ketamine
What treatments for pain affect the brain?
- Non-drug treatments □ Psychological - Drug treatments □ Paracetamol □ Opioids □ Amitriptyline □ Clonidine
What are the advantages of paracetamol?
- Cheap, safe
- Can be given orally, rectally or intravenously
- Good for:
□ Mild pain (by itself)
□ Mod-severe pain (with other drugs)
What are the disadvantages of paracetamol?
Liver damage in overdose
What are the advantages of NSAIDs?
○ Advantages
- Cheap, generally safe
- Good for nociceptive pain
- Best given regularly with paracetamol (Synergism)
What are the disadvantages of NSAIDs?
Gastrointestinal and renal side effects plus sensitive asthmatics
Give examples of NSAIDs
Aspirin, ibuprofen, diclofenac
What are the advantages of codine?
- cheap, safe
- good for mild to moderate acute nociceptive pain
- Best given regularly with paracetamol
What are the disadvantages of codien?
- constipation
- not good for chronic pain
What is tramadol?
Has a week opiod effect plus it is an inhibator of seritonin and noradrenalin uptake (modulation)
